Generally speaking, if a text or email is not clear, I think a person should ask follow up questions. Why waste time readng into what was said? Just ask for clarification. "Does it work better if we plan for Sunday earlier in the day? Would 10:00 work?" No need to create "maybe this or maybe that" scenarios. For me, if i cannot joke around with a partner or ask what is meant if something seems off, it's not the relationship for me. So if these exchanges really do offend you, OP, maybe he's just not for you and that's okay! But based on what we have been told I don't personally think he is rude or sending you a message of wanting his way or the highway or keeping you as a backup plan. He came across , to me, as happily and appropriately conveying he wants to see you without being pushy.
Shortly after my divorce, I dated a guy who sometimes had to travel for business, usually to the other side of the world. His boss was notorious for saying, on Friday afternoon, "my assistant booked your travel to Germany. Get the info before you leave today." The flight out would be for that weekend. And my guy had no warning until Friday. I got a lot of "I am sorry" phone calls, calls from other countries and little gifts from around the world. What I did not get was time with him.
A few months ago, he contracted me with the idea of trying again. He changed compnies and rarely needs to travel outside the country.
I agreed to go out with him. He postponed.
We rescheduled. He postponed.
Again and again.
It has gotten to the point that my BFF and I make bets on how soon after we make plans will he text to postpone, reschedule or simply apologize.
In the meantime, I date other men who actually follow through.